Snap-acting electrical switch



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Aug. 25, 1964 E. COOPER SNAP-ACTING ELECTRICAL swncu 4 Sheets-Sheet 4 Filed July 5, 1960 United States Patent 3,146,329 SNAP-ACTING ELECTRICAL SWITCH Lawrence E. Cooper, Attleboro, Mass., assignor to Texas Instruments Incorporated, Dallas, Tex., a corporation of Delaware Filed July 5, 1969, Ser. No. 40,933 13 Claims. (Cl. 200-168) The instant invention relates to electrical switching devices, and in particular, to hermetically sealed, miniaturized switching devices.

It is one object of the instant invention to provide a new and improved miniaturized electrical switch.

It is another object of the instant invention to provide such a switch which is hermetically sealed.

It is another object of the instant invention to provide a new and improved diaphragm member which is particularly advantageous for use with a hermetically sealed miniaturized electrical switch of the class described.

Among the further objects of the instant invention are included the provision of a miniaturized, hermetically sealed electrical switch which is precise, relatively simple in construction and economical to manufacture, simple to calibrate, and parts of which can be mass produced and quickly and easily assembled into operative, fixed, calibrated relation.

Other objects will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which one of the various possible embodiments of the invention is illustrated:

FIG. 1 is a front elevational view, with parts broken away, of a switch according to the instant invention;

FIG. 2 is a top plan view of the switch shown in FIG. 1;

FIG. 3 is a view similar to FIG. 1, showing certain parts in exploded relation;

FIG. 4 is a bottom view of the switch shown in FIG. 1;

FIG. 5 is a sectional view taken on line 5-5 of FIG. 1;

FIG. 6 is a view similar to FIG. 5, with parts omitted for purposes of clarification;

FIG. 7 is an enlarged view of a portion of the switch (the switch shown in FIG. 1, with certain parts omitted for clarity) .to illustrate the par-ts in one operative position;

FIG. 8 is a cross sectional view taken on line 8-8 of FIG. 7;

FIG. 9 is a view similar to FIG. 7, showing the parts in a second operative position; and

FIG. 10 is a sectional view taken on line Ill-10 of FIG. 9.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

Dimensions of certain of the parts as shown in the drawings have been modified for the purposes of clarity of illustration.

In the provision of miniaturized, electrical switches, and particularly snap-acting miniaturized switches, considerable difiiculty in fabrication and calibration has been encountered because of inherent dimensional tolerances. These problems are particularly accentuated with hermetically sealed, miniaturized switches. Such switches, particularly snap-acting switches, generally permit very small actuating movement or movement differential, making calibration and manufacture exceeding difficult 3,146,329 Patented Aug. 25, 1964 and expensive. By movement differential is meant the distance traveled by an actuating member between the point of actuation and deactuation of the switch. It is thus difficult to provide a switch which will operate dependably and yet be miniaturized and also hermetically sealed.

The instant invention successfully solves these problems and provides a switch which can be easily fabricated, assembled into final operative position, and calibrated in spite of its miniaturized size and close dimen-, sional tolerances.

Referring now to FIG. 1, there is shown a hermetically sealed, electrical switch embodiment of the instant invention which is generally referred to by numeral 10. Switch includes a cylindrical shaped, open-ended housing or can 12, which may be formed, for example, of stainless steel. Disposed within can 12 is an electrical switching subassembly generally designated by numeral 2%). Electrical switching subassembly 20 is of the type which is adapted to be actuated upon the application of a force thereto. Illustrated in the drawings is an exemplary snap-acting switching mechanism of the type which is disclosed and claimed in a copending application, U.S. Serial No. 40,845 of Hadley K. Burch and Malcolm K. Parkhurst, filed on July 5, 1960, and entitled Snap-Acting Mechanisms now Patent No. 3,105,- 886. Reference may be had to this copending application for details of construction of this exemplary electrical switching mechanism.

Switching mechanism Zil includes a snap-acting element in the form of a W-blade 22 of the type shown and described in U.S. Patent No. 2,777,032, issued on January 8, 1957, and also described in the above-mentioned copending application. W-blade or element 22 includes a pair of outer legs 24 and 26 and a central leg 28. Central leg 28 carries, on its free end, a pair of contacts 30 and 32. Legs 24 and 26 are provided respectively with apertures 34 and 36 for mounting said legs respectively on a pair of supporting pins 38 and 40. As more fully described in the above-referenced copending application, mounting pins 38 and 4d are so spaced as to force legs 24 and 26 toward each other and to stress the element 22 into a dished configuration whereby central leg 28 is urged out of the plane formed by legs 24- and 26. Central leg 28 thus can assume either of two positions on opposite sides of the plane formed by legs 24 and 26. It is to be understood that either one or both of these positions of opposite configuration may be relatively stable, depending on restraints to movement of leg 28 which are provided.

It should be understood that casing 12, although shown in cylindrical form, is tubular and may also have a rectangular or polygonal shaped cross section if desired. The word tubular describing the casing 12 as employed variously throughout the specification and claims, is intended to include cylindrical, as well as rectangular and other polygonal, cross sectional shapes.

Switch subassembly 20 includes a base comprising a flanged metallic ring 42 in which is infused a glass filler or header 44 with electrically conductive terminals 46, 48 and 50 embedded in and fused to the glass and projecting therebeyond in mutually insulated relationship. As clearly shown in the drawings, electrically conductive terminal 46 extends through the header 44 and on its inner end is provided with an enlarged shoulder or flange 52 and a neck 54. Switch 20 includes an electrically conducting switch support plate 56 fixedly secured to electrically conducting terminal 46 at collar 52. Support plate 56 is mounted on neck 54 and secured to terminal 46 and flange 52 in electrically conducting relation therewith. Supporting pin 40 is eccentrically mounted on a supporting post 64 which in turn is mounted on support plate 56 for relative rotatable adjustment. Mounting pin 38 is mounted on and carried by a post 66 which in turn is mounted on and supported by switch plate 56, as clearly shown and more fully described in the above-referenced copending application. Posts 64 and 66 have chamfered surfaces adjacent mounting pins 38 and 40 to permit legs 24 and 26 of W blade element 22 to flex thereabout and snap center leg 28 to actuate contacts 30 and 32, upon the application of a force to the outer portions of legs 24 and 26, adjacent their respective apertures.

Switch support plate 56 is provided with an upturned tab 68 which serves to support one end of a T-shaped actuating arm 70. T-bar or actuating arm 70 includes two leg portions 74 and 76, each of which respectively includes a downturned tab 78 and 80. Each of arms 74 and 76 and portions of their respective tabs are provided with slots 82 and 84 for freely mounting actuator bar 70 respectively about mounting pins 38 and 40 in a position for tabs 78 and 80 to respectively engage the outward portions of legs 24 and 26 for actuation of the W blade element 22, as described in greater detail in the aforementioned copending application.

Switch 20 further includes a stationary contact 88 carried by one leg of an L-shaped contact arm 90 which is secured and in electrically conductive relation to terminal 50 (see FIG. 3) as by welding. Stationary electrical contact 88 is engageable with electrical contact 32. It is to be understood that legs 24 and 26 are in electrically conductive relation with mounting pins 38 and 40, the latter of which are connected in electrically conductive relation with switch plate 56. Switch 20 also includes a second L-shaped contact arm 92 which is electrically connected to electrical terminal 48, as by welding or brazing. L-shaped contact arm 92 provides a bent-over portion 94 which includes a contact portion 96 which is adapted to mate with electrical contact 30 carried by leg 28 of W blade 22.

Referring now to FIGS. 7-10, upon the transmission of a force to actuating T-bar 70, the latter will depress tabs 78 and 80, which in turn exert a twisting motion or turning moment against the marginal edges of legs 24 and 26. The turning moment imparted to the ends of legs 24 and 26 will cause center arm 28 to snap upwardly from the contacts 32, 88 closed position, as shown in FIG. 7, to a position in which these contacts are open and contacts 30 and 96 are closed, as shown in FIG. 9. Release or suflicient abatement of the downwardly extending force transmitted to T-bar 70 will permit the center leg 28 to snap back from the FIG. 9 position to the FIG. 7 position. It is to be understood that center leg 28, when in the FIG. 7 position, is in a position of relative stability. However, due to the spacing of portion 94 (see FIG. 9) of L-shaped member 92, the FIG. 9 contacts 30, 96 closed position of leg 28 is not one of relative stability, and upon removal of the force applied to the T-bar actuator, leg 28 will snap back to the contacts 32, 88 closed position shown in FIG. 7.

Switch includes a diaphragm member generally referred to by numeral 100, as best seen in FIGS. 1 and 2. Diaphragm member 100 includes a first or main body portion 102 which is adapted to deflect under an applied force. Main body portion 102 is substantially circular in shape, as best seen in FIG. 2, and preferably includes at least one convoluted portion 104. Convolution 104, in addition to advantageously increasing the deflection of the diaphragm under an applied force, serves additional functions to locate an actuating button 106 and to stiffen the area of the diaphragm encompassed by the annularly extending convolution to facilitate welding of button or abutment 106 thereto. By stiffening this Weld area, weld ing of the button 106 to the diaphragm can take place without incurring substantial deformation of the diaphragm at this area. Further, this stiffening advantageously obviates the necessity of a backing member for welding in spite of the fact that the diaphragm is ordinarily formed of very thin gauge material. In practice, main body portion 102 of the diaphragm member is preferably dished upwardly, as shown, to increase the amount of its useful deflection. It is to be understood that such dishing is only preferable and that the diaphragm could also be flat.

Diaphragm member 100 further includes a circumferentially, peripherally and transversely extending flange .110. Flange 110 is formed integrally with main body portion 102 of diaphragm 100 to form a cup-shaped member which is adapted to be slidably inserted about the closed end of can 12, as shown in FIGS. 1 and 3. Flange 110 advantageously permits securement of diaphragm member 100 to casing 12 by means of welding as at 112 (see FIG. 1). The welding at 112 may, for example, conveniently be a seam weld. It is preferred that the welding of flange 110 to can 12 takes place adjacent the free end of the flange, remote from the main diaphragm portion 102, to advantageously permit maximum utilization of the entire diaphragm area of portion 102 for maximum defiective movement under a given applied force. The unique construction and arrangement of flange 110, when secured to can 12, permit the peripheral edges of the diaphragm to deflect radially outwardly and to flex about its weld point or weld line to can 12 to permit even greater deflection or center travel of the diaphragm under a given force.

The unique miniaturized switches according to the instant invention can be produced in extremely small sizes. For example, switches according to the instant invention have been made as small as 0.320" in diameter and 0.440" in length, with a total weight of approximately of an ounce or one gram. In view of the relative dimensions of the can and diaphragm, the cup-shaped diaphragm advantageously facilitates welding thereof to the can and advantageously permits locating the weld in an isolated, non-critical area, where weld and heat stresses do not present any adverse effects to calibration and performance of the diaphragm and switching mechanism. Further, flange 110, although it advantageously permits Welding at a convenient location and permits maximum utilization of the diaphragm main body 102, uniquely does not necessitate any substantial increase in diameter of the diaphragm or in overall size of the switch 10.

It is to be understood that although only one convolution has been illustrated, diaphragm 100 may include two or more convolutions, if desired. Diaphragm 100, as thus far described, is adapted to be deflected under an applied force. Such an applied force may, for example, be a mechanical force or be due to pressure exerted by gases, etc. It is to be understood that diaphragm 100 may also exert a downward deflection in response to thermal changes. For example, diaphragm member 100 could be formed of a thermally responsive bimetal or trimetal, and may also be deformed or dished to provide a thermally responsive, snap-acting element. The operation of such a thermally responsive, snap-acting element is similar to that described in the US. Patent 1,448,240 to J A. Spencer, issued March 13, 1923.

It is to be understood that it is within the purview of the invention to provide a dished diaphragm which is not of the thermally responsive type, and which may be of either the creep-acting or snap-acting type, depending on such variables as the shape and amount of dishing, type and thickness of material employed, etc. Where a mechanically snap-acting diaphragm is employed as a pressure sensitive member, the button 106 and convolution 104 may be omitted, if desired.

Referring now to FIG. 1, the upper closed end portion 120 of can 12 is deformed and includes a raised central portion 122. Depressed or deformed closed end portion 120 extends radially inwardly adjacent the peripheral cylindrical outer surface of can 12, and provides an annularly extending portion 124 upon which diaphragm 100 rests, as best seen in FIG. 1. Raised portion 122 of depressed portion 120 provides an aperture 126 in which is disposed a cylindrical sleeve 128. Cylindrical sleeve 128 includes an annularly extending flange 130 adjacent the upper surface thereof, as shown in FIG. 1. Flange 130 rests on the upper surface of raised portion 122 and serves as a stop to limit downward deflective movement of diaphragm 100. Sleeve 128 serves the dual function of (1) a stop member through flange 130, as described above, and (2) that of mounting and guiding a motion-transfer pin 140 for reciprocal sliding movement therein, as best seen in FIGS. 1 and 3.

Motion-transfer pin 140 is engageable with the underside of the central portion of diaphragm 100 opposite button 106 and also engages the upper surface of actuator bar 70, as best seen in FIGS. 1 and 3. Motion-transfer pin 140 is adapted to move downwardly upon deflection of diaphragm 100 to move actuator bar 70 to act on W blade 22 to actuate the contacts carried by leg 28 in the manner described above.

The spacing between the upper surface of stop or flange 130 and the lower surface of the center portion of the diaphragm, which distance is designated by the letter Z (see FIG. 1), is important in assuring proper operation of the switching mechanism and the diaphragm member 100. Deformed sections 120 and 122 of can 12 are so shaped that the distance Z will be great enough to provide adequate center travel of the diaphragm under an applied force for actuation purposes, and yet be small enough to insure desired repeatability of the diaphragm and avoid substantial permanent deformation of the diaphragm under large applied forces. It is to be understood that, if desired, flange 130 and sleeve 128 could be formed integrally with deformed portion 122 of can 12. The distance between the under surface of diaphragm 100 in the unstressed condition, and the top surface of actuator bar 70, is also carefully selected so as to insure proper actuation of the switch. As will be described in greater detail below, although proper selection of the distance between the under surface of the diaphragm 100 and the top surface of actuator bar 70 is important, the tolerance dimensions of pin 140 are not critical because of a unique and advantageous method of calibration afforded by the construction of the instant invention.

Ring 42 of the base is provided with an annular and longitudinally extending flange 43, which is conveniently of a relatively thin gauge. Annularly extending flange 43 is welded to the can 12, as by seam welding, as at 45, to hermetically seal the switching subassembly 20 within the can 12 and to fix the switch in final assembled relation within the can 12.

Referring now to FIG. 3, subassembly 20 is slidably inserted into can 12, in the direction of the arrow shown in FIG. 3. Assembly of switch 10 is easily accomplished in the following manner:

(1) Insert sleeve 128 into aperture 126 in can 12;

(2) Slidably mount diaphragm 100 about can 12 and weld diaphragm 100 thereto, in the manner described above;

(3) Insert pin 140 into sleeve 128;

(4) Insert a sleeve 13 formed of an electrically insulating material into can 12, as shown; and

(5) Slidably insert switching subassembly 20 into the can 12 in the direction of the arrow shown in FIG. 3.

It is to be noted that during assembly, switching subassembly 20, can 12 and parts associated therewith, would be oriented in a transverse direction rather than vertically, as shown in FIG. 3.

Calibration of switching mechanism 20 is accomplished by the amount of insertion of switching subassembly 20 into the can until actuator bar 70, motion transfer pin 140 and diaphragm 100 are in a predetermined desired calibrated relation. Thereafter, relatively thin flange 43 is welded to can 12 as at 45, to both hermetically seal the electrical switching mechanism 20 within can 12, and

to fix the switching mechanism relative to said can infinal, calibrated, operative position. The thin wall flange 43 is relatively thin and flexible, and advantageously serves to localize heat and welding stresses to preclude them from deleteriously affecting the frangible glass header 44. Further, the unique arrangement of flange 43 permits locating the switching subassembly 20 within can 12 in final adjusted position with the T-bar 70 engaging transfer pin 140, the latter of which is also in engagement with the lower surface of diaphragm 100. It is to be understood that the required applied force on the diaphragm and the travel distance necessary for actuation and de-actuation of the electrical switch, can be varied or calibrated by the amount and extent of insertion of switching mechanism 20 into the can 12, and by the force applied against the pin and consequently against the diaphragm by the switching assembly upon insertion thereof into the can and sealing thereof, as by welding, to the can 12. Thus, flange 43, after being welded to can 12 as at 45, permanently maintains switching assembly 20 within can 12 in final, fixed, assembled, calibrated relation, and also in a hermetically sealed condition. Further, relatively thin flange 43 advantageously provides a convenient area for welding the switching assembly to the can. This is extremely advantageous in view of the relatively small or miniaturized size of the entire switching assembly, and the extremely limited cross sectional area or mass which is available for welding. Further, the unique arrangement of flange 43 permits the convenient welding mentioned above without increasing the mass or overall size of the switch 10. It should be understood that flange 43 can be secured to can 12 not only by welding, but by brazing, soldering or other convenient means, which will provide a hermetic seal and will maintain the switching assembly 20 in fixed, final adjusted or calibrated relation within the can 12.

Flange 43 further advantageously provides a convenient means for securement of the entire switch 10 within other enclosures which may be necessary for particular applications. For example, the miniaturized switch 10 can be conveniently inserted into a screw threaded housing and switch 10 can be welded thereto as at flange 43 without upsetting the calibration of the switch or deleteriously affecting the frangible glass seal.

In view of the above, it can be seen that the instant invention provides a miniaturized, hermetically sealed switch which can be easily and quickly produced at low cost. The instant invention provides a hermetically sealed, miniaturized switch which is precise, can be easily, quickly and uniquely calibrated and easily and quickly assembled. Further, the switch of the instant invention includes a diaphragm which affords maximum utilization of the diaphragm area which is permitted by the unique and advantageous mounting thereof on the can 10.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings, shall be interpreted as illustrative and not in a limiting sense, and it is also intended that the appended claims shall cover all such equivalent variations as come within the true spirit and scope of the invention.

It is to be understood that the invention. is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in. various ways. Also it is to be understood that the phraseology or terminology and employed herein is for the purpose of description and not of limitation.

I claim:

1. An encapsulation for an electrical switching mechanism mounted on a base comprising in combination a tubular housing having a closed end and an open end, means associated with said closed end of said housing for actuating said switching mechanism upon movement thereof in response to a predetermined force, said switching mechanism and base being telescopically inserted into said tubular housing and initially abutting said means, said switching mechanism being inserted within said housing to a predetermined extent different from said initial abutting relation with said means whereby said switching mechanism is positioned in said housing in predetermined calibrated relation to said means; and said base being secured to said tubular housing to thereby fixedly mount said switching mechanism in final calibrated position within said housing.

2. The electrical switch as set forth in claim 1 and wherein said base includes a relatively thin peripherally extending flange portion and said relatively thin base flange portion being secured to said housing as by welding or the like.

3. The electrical switch as set forth in claim 1 and wherein said switch is hermetically sealed.

4. The electrical switch as set forth in claim 1 and wherein said switching mechanism comprises a pair of electrical contacts; and snap-acting means supporting one of said contacts for movement into and out of engagement with the other of said contacts.

5. An encapsulation for an electrical switching mechanism mounted on a base and adapted for miniaturization comprising in combination a tubular metallic housing having a closed end and an open end; said switching mechanism and base being slidably inserted into said tubular housing and secured thereto; means comprising a motion-transfer device associated with said closed end of said housing and engageable with said switching mech anism; said motion transfer device comprising a motiontransfer pin; said closed end of said housing including a guideway mounting said pin for reciprocal movement toward and away from said switching mechanism; a diaphragm member secured to said housing adjacent the closed end thereof and engageable with said motion-transfer device to actuate said switching mechanism upon movement thereof in response to a predetermined force; said housing being substantially of cylindrical configuration; said diaphragm member comprising a diaphragm section of substantially circular configuration, at least a portion of said section including a transversely extending flange portion formed integrally therewith adjacent the periphery thereof; said section including at least one convolution of circular configuration substantially concentric with the circular configuration of said section; said section having a dished configuration; and said flange portion being telescopically disposed about said housing and secured to said housing as by welding or the like.

6. The electrical switch as set forth in claim 5 and wherein said diaphragm member includes an abutment member secured to said diaphragm section and located within the area defined by said one convolution.

7. An encapsulation for an electrical switching mechanism mounted on a base and adapted for miniaturization comprising in combination a tubular metallic housing having a closed end and an open end; said switching mechanism and base being slidably inserted into said tubular housing and secured thereto; means comprising a motion-transfer device associated with said closed end of said housing and engageable with said switching mechanism; said motion-transfer device comprising a motiontransfer pin; said closed end of said housing including a guideway mounting said pin for reciprocal movement toward and away from said switching mechanism; a diaphragm member secured to said housing adjacent the closed end thereof and engageable with said motiontransfer device to actuate said switching mechanism upon movement thereof in response to a predetermined force; said diaphragm member comprising a diaphragm section of substantially circular configuration; said section including a peripherally, circumferentially and transversely extending flange formed integrally therewith; said section including at least one convolution of circular configuration substantially concentric with the circular configuration of said section; said housing being substantially of cylindrical configuration; and said flange portion being telescopically disposed about said housing and secured to said housing as by welding or the like.

8. An encapsulation for an electrical switching mechanism mounted on a base and adapted for miniaturization comprising in combination a tubular metallic housing having a closed end and an open end; said switching mechanism and base being slidably and telescopically inserted into said tubular housing and secured thereto; means comprising a motion-transfer device associated with said closed end of said housing and engageable with said switching mechanism; said motion-transfer device comprising a motion-transfer pin; said closed end of said housing including a guideway mounting said pin for reciprocal movement toward and away from said switching mechanism; a metallic diaphragm member secured to said housing adjacent the closed end thereof and engageable with said motion-transfer device to actuate said switching mechanism upon movement thereof in response to a predetermined force; said diaphragm member comprising a diaphragm section; a flange portion extending from said section at an angle thereto; said flange portion being telescopically disposed about said housing and secured to said housing externally thereof as by welding or the like; said closed end portion of said housing being spaced from an interior surface of said diaphragm section by a predetermined amount; and said closed end portion of said housing including stop means cngageable with said diaphragm section to limit movement thereof in a direction toward said switching mechanism.

9. An encapsulation for an electrical switching mech anism mounted on a base and adapted for miniaturization comprising in combination a tubular metallic housing having a closed end and an open end; said switching mechanism and base being slidably and telescopically inserted into said tubular housing and secured thereto; means comprising a motion-transfer device associated with said closed end of said housing and engageable with said switching mechanism; said motion-transfer device comprising a motion-transfer pin; said closed end of said housing including a guideway mounting said pin for reciprocal movement toward and away from said switching mechanism; a metallic diaphragm member secured to said housing adjacent the closed end thereof and engageable with said motion-transfer device to actuate said switching mechanism upon movement thereof in response to a predetermined force; said diaphragm member comprising a diaphragm section; a flange portion extending from said section at an angle thereto; said flange portion being telescopically disposed about said housing and secured to said housing externally thereof as by welding or the like; said base including a relativey thin peripherally extending flange portion; and said relatively thin base flange portion extending around and adjacent an interior wall of said tubular housing and also being secured to said housing as by welding or the like.

10. The electrical switch as set forth in claim 9 and wherein said switching mechanism is hermetically sealed within said housing.

11. A hermetically sealed encapsulation for an electrical switching mechanism mounted on a base and adapted for miniaturization comprising in combination, a tubular metallic housing having an open end and a closed end; said base having a relatively thin peripherally extending metallic flange portion and a central portion of electrically insulating glass material in which is mounted an electrically conductive terminal for said switching mechanism, said peripherally extending flange portion extending in a direction away from said insulating glass portion whereby to minimize the transfer of heat and stresses developed during welding or the like to said glass portion, said switching mechanism and base being slidably and telescopically inserted into said tubular housing with said peripherally extending flange portion disposed around and closely adjacent to an interior wall of said tubular housing, motion transfer means associated with said closed end of said housing and engageable with said switching mechanism for actuating the latter in response to predetermined movement of said motion transfer means; said base and switching mechanism being inserted into said tubular housing to a predetermined extent with said switching mechanism positioned in predetermined calibrated relation to said motion transfer means, and said flange being secured as by welding or the like to said tubular housing to thereby fixedly mount said switching mechanism in final calibrated position within said housing.

12. A hermetically sealed encapsulation for an electrical switching mechanism mounted on a base and adapted for miniaturization comprising in combination, a tubular metallic housing having an open end and a closed end; said base having a relatively thin peripherally extending metallic flange portion and a central portion of electrically insulating glass material in which is mounted an electrically conductive terminal for said switching mechanism, said peripherally extending flange portion extending in a direction away from said insulating glass portion whereby to minimize the transfer of heat and stresses developed during welding or the like to said glass portion, said switching mechanism and base being slidably and telescopically inserted into said tubular housing with said peripherally extending flange portion disposed around and closely adjacent to an interior wall of said tubular housing; a motion transfer pin disposed for reciprocal sliding movement relative to said switching mechanism within an exteriorly communicating guideway provided by said closed end of said housing, a diaphragm member disposed exteriorly of said motion transfer pin and having a peripherally extending flange telescopically disposed about and secured to said closed end of said tubular housing as by welding to hermetically seal said closed end of said housing and to transmit externally applied forces to said motion transfer pin for actuating said switching mechanism; said base and switching mechanism being inserted into said tubular housing to a predetermined extent with said switching mechanism positioned in predetermined calibrated relation to said motion transfer pin, and said base flange being secured as by welding or the like to said tubular housing to thereby fixedly mount said switching mechanism in final calibrated position within said housing.

13. The electrical switch as set forth in claim 11 and said switch including an insulating sleeve disposed in said housing and intermediate at least a portion of said switching mechanism and said housing.

References Cited in the file of this patent UNITED STATES PATENTS 503,504 Pooley Apr. 6, 1939 2,327,069 Satterlee Aug. 17, 1943 2,375,387 Robbins May 8, 1945 2,440,943 Gonsett May 4, 1948 2,451,176 Schellman Oct. 12, 1948 2,595,967 McCloy May 6, 1952 2,598,563 Konle May 27, 1952 2,729,720 Jacobs Jan. 3, 1956 2,777,032 Burch Jan. 8, 1957 2,790,881 Schueler Apr. 30, 1957 2,854,536 Beer Sept. 30. 1958 2,873,326 Kurtis Feb. 10, 1959 

1. AN ENCAPSULATION FOR AN ELECTRICAL SWITCHING MECHANISM MOUNTED ON A BASE COMPRISING IN COMBINATION A TUBULAR HOUSING HAVING A CLOSED END AND AN OPEN END, MEANS ASSOCIATED WITH SAID CLOSED END OF SAID HOUSING FOR ACTUATING SAID SWITCHING MECHANISM UPON MOVEMENT THEREOF IN RESPONSE TO A PREDETERMINED FORCE, SAID SWITCHING MECHANISM AND BASE BEING TELESCOPICALLY INSERTED INTO SAID TUBULAR HOUSING AND INITIALLY ABUTTING SAID MEANS, SAID SWITCHING MECHANISM BEING INSERTED WITHIN SAID HOUSING TO A PREDETERMINED EXTENT DIFFERENT FROM SAID INITIAL ABUTTING RELATION WITH SAID MEANS WHEREBY SAID SWITCHING MECHANISM IS POSITIONED IN SAID HOUSING IN PREDETERMINED CALIBRATED RELATION TO SAID MEANS; AND SAID BASE BEING SECURED TO SAID TUBULAR HOUSING TO THEREBY FIXEDLY MOUNT SAID SWITCHING MECHANISM IN FINAL CALIBRATED POSITION WITHIN SAID HOUSING. 